Here's my 2 cents. All this happened while I was overseas.
I've been with AMEX for almost 15 years. Never missed a payment. Put through hundreds of thousands easily. Referred a dozen of people. All of this down the drain.
All I did was send 3 payments via PayPal to my s.o., she did the same. First time ever doing such a thing. And we did this because we were looking to buy a car but had the cash tied into a loan and did not want to redraw, so thought why not just do this (gives us time until next month) and earn points along the way -dealer did not want to touch amex btw.
I get a poorly worded - think Engrish, email from Account Services to call. I did so to be drilled about the transactions and be told that the accounts will be all cancelled. All reserve/qff/plat charge)!!
The agent wouldn't explain why these transactions contravened the terms and conditions. I asked her to quote the specific line and all she did was promise to send an email (she later did but attaching a totally irrelevant document).
I pressed the agent hard and asked to be lodge a dispute as per the IDR process guidelines (FOS imposed/lingo). After ignoring the request a couple times, she went ahead with it. And was promised a response within a day or two (never happened).
Upon following up the second day (cards now all cancelled btw) I was given the cold shoulder and told to write to the executive team whoever that is. And that the dispute/complaint was rejected - cancellation stands.
I spent that afternoon preparing the language for a FOS complaint (seeking reinstatement of accounts, fee refunds and compensation) which got picked up early this week. Now waiting on response from AMEX.
My wife's account got suspended just this week. She is still overseas. Dreading having to jump through hoops again. Who has time?!
One thing that agent said that I found interesting: 'several of our clients are doing this (whatever this means) and we're cancelling their accounts.
BTW, contrary to what the accounts services team claim that the Exec team can only be reached via snail mail. Their email address is actually listed on the FOS website. Also a note to others, contrary to what an agent might say, there are options to complain/dispute the account suspension/closure.
And while searching for similar experience, I came across this from 14 years ago:
Warning - You Can't Rely on your American Express Card
Seems like AMEX is a dinosaur when it becomes to business processes, almost nothing has changed since then...